SURVEY OF TILLANDSIA-RECURVATA L - PREFERENCE, ABUNDANCE AND ITS SIGNIFICANCE FOR NATURAL FORESTS

The ball moss (Tillandsia recurvata L.) is an epiphytic weed that causes a deleterious effect upon its host when abundance is high. Because of its increasing abundance a survey was carried out in three different sites of the Province of Buenos Aires, Argentina, covering about 1000 ha and 457 trees from 114 species, belonging to 79 genera and 44 botanical families. A scale of abundance, from 0 (no epiphytes) to 4 (almost the whole host with epiphytes) was used to estimate the T. recurvata population. In the Riparian Forest of Punta Lara almost 100% of the surveyed trees have an abundance of 0 and 1; the average for all sites showed 58% of the individuals with an abundance of 1, 10% with an abundance of 2, 8% with 3 and less than 8% with abundance 4. Although there was no significant correlation between the diameter of the hosts and abundance of the epiphyte, 90% of the trees with the greatest abundance had a diameter greater than 0.40 m. Three host types were defined according to the epiphyte average abundance and preference: Group I, high susceptibility; Group II, moderate susceptibility; Group III, epiphyte avoiders. Species with rough, deep and no exfoliating barks, with horizontally growing branches, and no exudating allelophatic compounds or latex, which favour T recurvata anchorage, are potential members of Group I. while species with smooth, exfoliating and continuous bark, branches growing close to the main trunk, and exudating allelopathic compounds or latex are potential members of Group III or epiphyte avoiders. From this survey eight host species were seen to be heavily laden with T recurvata, regardless of the growth habit of the host (evergreen or deciduous), representing different genera and botanical families. It is important to point out that individuals heavily laden with T recurvata showed signs of decline. As commercial forests and plantings are carried out under conditions that promote rapid growth, natural forests are more susceptible to the invasion of this epiphyte; therefore some measures should be taken to preserve or recover them; for example, the successful chemical control proposed by our research group.